bandy@lll-crg.ARPA (Andrew Scott Beals) (06/20/85)
Again, one of the basic things that you want to avoid is using your
brakes - whomp on the gas instead - or if your rpms are too low to
get a moderate surge of acceleration out of that, downshift and then
whomp (this is for snow, I haven't gone out and found myself some
sand yet). You'll end up drifting a bit, but at least you won't have
your rear end sliding around to the front like you do if you clutch
or (shudder) hit the brakes.
If you live near enough to where they have lots of cold and snow,
go ice-racing for a day - it'll be some of the best money you've
spent on your truck.
--
andy beals bandy@lll-crg.arpa {sun!lll-crg,ihnp4!mit-eddie}!bandy
If you love something, hit it with a club. If it comes back to you, then
it must really like you.fowler@uw-beaver (Rob Fowler) (06/24/85)
Let me throw in my 2 cents worth on controlling 4wd. My 72 ScoutII has manual Warn hubs on the front end. As a result when in 4wd the front wheels turn exactly the same number of revolutions as the rear ones (modulo the differentials at each end). This is great for pulling one's self out of mud, ditches, etc. It seems to have an unfortunate side effect on snow and ice, however. With the wheels at either end being driven and the others freewheeling a rear or front wheel drive vehicle can be brought out of a skid (fishtail, spin, whatever) by pointing the front wheels in the direction you're going (thus getting them rolling again), and doing the appropriate thing with the throttle (usually nothing). When the rear wheels get lined up again, they should be rolling also. The net effect is that the front wheels are encouraged to make slightly more revolutions than the rears, thus getting you going straight. Growing up in New England I did a lot of snow and ice driving in both rear and front-wheel drive vehicles and being young and stupid I got plenty of chances to stop skids and incipient spins. In my Scout on ice/snow in 4wd I learned that the conventional techniques for stopping skids just don't work. I learned this when the vehicle was new on a long (1/2 mile) icy mountain downhill in Vermont about 10 years ago. I made about 6 360 degree turns at about 40 mph while bouncing between the 6 foot snowbanks that were fortunately on either side of the road. I fought it all the way, but whenever I got things straightened out it did not continue to roll straight and stably, rather it slid through to the other side. The fishtailing increased in amplitude rather than decreased. The vehicle and I both survived. (I did have to get help shoveling all the snow out of the engine compartment from one of the guys I managed to miss.) After this incident a friend who had a siimilar vehicle with automatic Warn hubs (i.e. in the off position they have a freewheeling clutch) and I got together in a big parking lot during an snow/slush/ice storm to do some experimenting. (Doesn't everyone in snow country do this for winter entertainment?) My vehicle in 2wd behaved as expected. His in 2wd and 4wd with hubs on auto also behaved well. I locked-up 4wd both required more radical maneuvers to break them loose, but once sliding we could not figure out how to quickly get back in control once the slide was started. The conclusion was that because the fronts and rears were locked together that there was no way for the fronts to turn more than the rears to let the front end get ahead and stay there. After that I got real careful about overestimating the safe speed I could handle in 4wd on snowy and icy roads. Of course our analysis does not apply to 4wd vehicles with a middle differential such as the full time 4wds that were popular a few years ago. Have any of you had similar experiences? Rob Fowler (fowler!uw-beaver or fowler@washington.arpa) P.S. Anyone out there want to buy a '72 Scout II real cheap? All it needs is to have its rear differential replaced.
jeepcj2a@fluke.UUCP (Dale Chaudiere) (06/25/85)
> Growing up in New England I did a lot of snow and ice driving in > both rear and front-wheel drive vehicles and being young and stupid > I got plenty of chances to stop skids and incipient spins. > > In my Scout on ice/snow in 4wd I learned that the conventional techniques > for stopping skids just don't work. I learned this > when the vehicle was new > on a long (1/2 mile) icy mountain downhill in Vermont about 10 years ago. > I made about 6 360 degree turns at about 40 mph while bouncing > between the 6 foot snowbanks that were fortunately on either side > of the road. I fought it all the way, but whenever I got things > straightened out it did not continue to roll straight and stably, > rather it slid through to the other side. The fishtailing increased > in amplitude rather than decreased. The vehicle and I both survived. > (I did have to get help shoveling all the snow out of the engine > compartment from one of the guys I managed to miss.) > > After this incident a friend who had a siimilar vehicle with > automatic Warn hubs (i.e. in the off position they have a freewheeling > clutch) and I got together in a big parking lot during an snow/slush/ice storm > to do some experimenting. (Doesn't everyone in snow country do this for > winter entertainment?) My vehicle in 2wd behaved as expected. His in > 2wd and 4wd with hubs on auto also behaved well. I locked-up 4wd > both required more radical maneuvers to break them loose, but once > sliding we could not figure out how to quickly get back in control > once the slide was started. The conclusion was that because the > fronts and rears were locked together that there was no way for the > fronts to turn more than the rears to let the front end get ahead and > stay there. After that I got real careful about overestimating > the safe speed I could handle in 4wd on snowy and icy roads. > > Of course our analysis does not apply to 4wd vehicles with a middle > differential such as the full time 4wds that were popular a few years > ago. > > Have any of you had similar experiences? > > Rob Fowler (fowler!uw-beaver or fowler@washington.arpa) > Yes, and the shorter the wheel base the worse the effect. As you stated if you apply gas to try to pull out of the skid, the rear wheels also turn faster and the back end comes around even faster. This is what I do on ice or compact snow: 1. Do not apply the brakes!! We all the effect that has. 2. Let off the gas. 3. Try to steer out of it. 4. If it is really bad, put chains on the rear tires so they don't come around in the first place. Also, make sure your rear tires have a good biting edge.